Wideband frequency analyzers may be used to analyze the spectral characteristics of a received electromagnetic signal. As a result, wideband frequency analyzers are useful in many different signal processing applications. For example, wideband frequency analyzers may be used in various types of communication systems, including satellite and microwave communication systems, radar systems, radar threat receiver systems, studio sound recording systems, and the like.
The analysis of a received electromagnetic signal generally includes determination of the frequency, or frequency band, associated with each signal, and may also include other signal characteristics, such as a transform function associated with the signal. Wideband frequency analyzers operate over a specific frequency range. The wideband frequency analyzer can detect and analyze any signal that has a frequency within the frequency range of the wideband frequency analyzer.
In multi-signal applications, the wideband frequency analyzer may receive a broadband signal that comprises multiple individual signals that are received simultaneously. Using the wideband frequency analyzer, the characteristics of each signal within the broadband signal may be analyzed. In particular, each signal within the broadband signal has a specific frequency, or frequency band, associated with the respective signal. For example, a communication system may utilize a broadband signal that contains hundreds or thousands of individual signals, with each individual signal comprising, for example, a data stream for a number of phone calls.
One important technique for accomplishing wideband spectral analysis employs transversal filters to implement the chirp transform. Typical wideband frequency analyzers implement the chirp transform with transversal filters built using either surface acoustic wave (SAW) devices or tapped, superconducting delay lines. Such wideband frequency analyzers have a limited frequency detection range. In particular, conventional SAW device wideband frequency analyzers are generally limited to a frequency bandwidth on the order of 500 MHZ. Conventional high temperature superconducting (HTS) tapped delay line wideband frequency analyzers are generally limited to a frequency bandwidth on the order of 4 Ghz. Further, conventional HTS device wideband frequency analyzers also have limited frequency resolution capabilities due to limitations on the filter delay times achievable with such devices. For example, conventional HTS device wideband frequency analyzers are generally limited to a frequency resolution on the order of 25 MHZ.
Many conventional wideband frequency analyzers also have a limited dynamic range that cannot be electronically adjusted. In particular, conventional SAW and HTS wideband frequency analyzers utilize fixed taps for apodization, i.e., amplitude weighting. The fixed taps do not allow the apodization to be electronically corrected to correct for signal irregularities, such as chirp and other non-linearities.